Author's Notes: I blame Livejournal for this. (This was and is never going to be a bigger story, just so you know. Feel free to continue it.)

Most of the myth stuff is vaguely correct as far as I know, but there are a lot of different myths, so emphasis on the vaguely. I've never been west of the Faroe Islands or east of St Petersburg, so any inaccuracies as to how things work elsewhere are caused by my lack of travelling and nativity. (Besides, my sense of geography sucks.)

Summary: "Calm down, Morgan," Prentiss said dryly. "I thought you liked this kind of movie."

Warnings: er... zombies? a little gory?

standard operating procedures (in case of zombie apocalypse)

"I mean – what the hell?"

"Calm down, Morgan," Prentiss said dryly. "I thought you liked this kind of movie."

"Stop it, both of you," Hotch said, taking up position by the far corner of the house. It wasn't an ideal location for defence, but it would have to do. The streets were even more dangerous than usual these days. "JJ, cover the other corner."

JJ nodded and went to take her position with no small amount of apprehension, blonde hair matted with dried blood and dirt. There was a small cut by her left eyebrow that reopened every time she frowned.

Reid leant against the wall next to Prentiss, while Morgan was trying not to pace, though they could all sense his aggravation. Reid's leg was still giving him some trouble – his slight limp had worsened just in the last few hours.

They'd had a case in Williamsburg, and were driving back to Quantico through Richmond when it hit – it was just a glimpse of light, like a rocket bursting over the rooftops. The debris had rained down beneath it, and that was when things got weird. The roads were soon filled with cars pointing in every direction but forward, so they had to abandon their cars and get across town on foot, however long that would take, and try to find a car that could bring them back to headquarters and protect them from interlopers; the people they'd seen so far were either dead, frantic or both.

None of them were sure what was going on, but whatever it was turned perfectly rational people into ruthless killing machines.

They'd been on foot for almost two full days, but the interruptions kept piling up – they'd had to stay put all morning because of suspicious activity, and had to take long detours around certain areas to stay out of sight.

"Have we managed to establish contact with Garcia yet?" Hotch said, glancing over his shoulder.

"No," Prentiss said, fingers moving across the keyboard of her laptop. "I can't even get access to a network."

"Shit," Morgan muttered. He looked tempted to hit the brick wall.

"Speak up if you notice anything strange," Hotch ordered. "Anything could be significant."

"Stranger than zombies?" Morgan said.

Hotch sent him a look; they didn't have time for breakdowns.

"Actually, they're more like the mythical vampire," Reid interjected, hands gesturing despite the gun in his hands. He must have noticed their uneasy looks, as he stopped waving his arms with a slightly sheepish look. "According to certain myths, they were corpses possessed by evil spirits. In some cultures they look human, in others their bodies are bloated or half-rotten with dark or purplish skin. The main characteristic is that they drink blood, but in most myths they didn't actually have fangs at all."

JJ glanced at him with an indulgent but tired expression before she returned to watching the street around the corner.

Morgan lifted an eyebrow. "I thought vampires had that whole suave thing going on."

"That's a 19th century fad," Reid said.

"Fad?" Prentiss said, sounding a little amused.

"I could say 'affectation', but 'fad' sounds a little less contrived."

"Not when you're the one saying it," Prentiss said.

"I'll say trend next time."

"Not that synonyms aren't interesting," Hotch interrupted, "But I think we're getting company."

"Damn it," Prentiss hissed under her breath. Her sleep rotation was approaching; she hadn't slept in two days.

"JJ, you see anything?" Hotch said.

"All clear."

"Morgan, stick with me. Reid, stay with us unless JJ calls for backup. Prentiss, you're not in any kind of shape to aim a gun right now. Just sit down until we find a place to set up camp."

"Got it," she muttered. She drew her gun and put it on the ground beside her, and kept trying to access a network. Garcia did this all the time, she reminded herself as she decided to try another network. It was connected to a government facility. "Yes," she hissed. "If I can just…"

The spattering of gunshots distracted her, but everyone seemed to be fine so far – at least, as fine as they'd been beforehand. She decided to keep an eye on JJ just in case, as dead people couldn't call for help.

Good thing, too.

"JJ, behind you!"

JJ whirled around and shot the- the thing right in the head. It fell over with a groan. She dealt with the second just as efficiently, and kept back until she was sure they were properly dead.

"You okay?" Morgan shouted – apparently they had a few more interlopers.

"We're fine," Prentiss called.

JJ had put on forensic gloves and appeared to be studying the… whatever they were. "Look at their eyes," she said.

Prentiss grabbed her gun as she got up, steadying herself against the wall. As she moved closer, she saw it, too. Bloodshot eyes, dilated pupils – she could hardly see the iris at all. "He looks like he's so high it's not even within the realm of an overdose."

JJ reached a gloved hand out to put it on the body's arm. "The skin is getting cold already. Feels strange, almost like fabric." From what they could see of the body, there were odd, bruise-like marks all over the bodies. A strip of skin stuck to her glove when she pulled away. "I don't think we should get any closer to them than necessary."

"That," Prentiss said. JJ gave her a quizzical look. "We can't afford breaking down, and it's easier not to think of them as people. Even if they still are…"

"We have to defend ourselves," JJ said softly. "Even if they're just sick."

"Exactly."

"Some say serial killers are just sick, too," JJ continued. "That doesn't mean we should let them be."

Prentiss heard the hint of a reprimand, and bowed her head in agreement. JJ wasn't technically a profiler – she was an agent – but she had more than a rudimentary knowledge of the human mind. She played politics, and if anyone understood how hard that was, it was Emily Prentiss.

She heard steps, and almost lifted her gun before she realised that they were Reid's. He bowed down beside JJ, also wearing gloves, and his eyes flicked across them.

"Strange," he muttered. "I've never heard of anything that can do this. Not even designed viruses."

"You think it's a virus?" Hotch said, moving closer as he gestured Morgan to keep watch in case any more ambushed them.

"Or a bacteria," Reid said. "I can't think of anything else that would fit."

"How do we fight this?" JJ said.

The silence wasn't encouraging.

...

"I've only ever experienced this in video games," Garcia's tinny voice said from the computer speakers. "And I'm pretty sure your batteries are running out, you need to find an outlet and I really hope you brought a charger."

"Sorry, Garcia," Prentiss said. "It's still in the car."

"Right," Garcia said. "Right. Well, I'll just try to give you an overview. The city is under quarantine. Your phones should still have a signal for the time being, but you should probably use only one at a time to save batteries, and we should have a check-in time to keep track of each other. Hotch, I just sent a map to your phone."

There was a pause.

"Garcia?" Prentiss prompted. "You okay?"

"I'm fine," Garcia said. "If knowing people you care about are in a zombie-infested town counts as fine."

"Just see what you can find out, okay?"

"Okay."

Beep.

"So much for knowing what this is," JJ muttered. Reid sent her a wan smile, but didn't say anything. She was grateful; this wasn't the time for empty platitudes.

"Hey, Reid," Morgan said. "You have any ideas to share with the class?"

Reid's eyes seemed to turn inward for a moment. "There were many techniques to prevent the undead from rising," he said. "People were often buried upside down, and sometimes the tendons of their knees were severed, so they wouldn't be able to climb out of their graves. If you put poppy seeds, sand or rice on the graves of suspected vampires, they wouldn't be able to get loose because they'd be occupied all night with counting the seeds. Also, the ground sinking together in graveyards was supposed to be a sign of the proximity of vampires, but that's just the coffins collapsing."

Morgan looked at him.

"No, not really."

"Headshots seem to work," Prentiss said.

"How much ammunition do we have?" Hotch said.

"Not enough," Prentiss said, sighing. They hadn't been able to bring anything from the car that weren't next to them or in their laps. "We could ask Garcia where the nearest hunting store or anything similar is located during the next check in."

"There's one about half an hour to the north," Reid said.

"Never mind," Prentiss muttered. JJ hid a smile behind her hand.

"We should bring back a sample," Reid said. "Does anyone have some sort of container?"

"I have a bottle of water," JJ said. "But I think water is more of a priority."

"We'll find one," Prentiss said. "It can't be that hard. Come on, Morgan."

A brief search around the neighbourhood resulted in three plastic bottles with holes burned through the side and a beer bottle without a cap.

"Does anyone have a piece of string?" Reid asked, pulling a candy wrapper out of his pocket. He bowed down by one of the bodies (male, Caucasian, mid-thirties, thin as a rail) and started cutting off a finger with a pocket knife, making sure not to get any blood on himself.

"Would this work?" JJ pulled a hair band from her pocket.

Reid grinned, covered the bottle cap with the candy wrap and twinned the hair band around the bottle top several times until it was as secure as it could be. He held it up triumphantly. Morgan looked like he was going to laugh - JJ elbowed him.

Hotch shook his head, but Prentiss noticed the barely-there quirk to his lips.

"Let's get back to headquarters," he said. There wasn't anything else they could do.